Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access EVA A.05.01

5 Understanding failover/failback scenarios
Metrocluster package failover/failback scenarios
This section discusses the package start up behaviors in various failure scenarios depending on
DT_APPLICATION_STARTUP_POLICY and replication mode. Table 7 describes the list of failover
scenarios.
Table 7 Replication Modes and Failover Scenarios
ResolutionDT_APPLICATION_STARTUP_POLICYReplication
Mode
Failover
Scenario
Data_Currency_PreferredAvailability_Preferred
N/ADR Group fails over and the package is started. The
behavior is not affected by the presence of the FORCEFLAG
file.
Synchronous
or Enhanced
Asynchronous
Remote failover
during normal
operations
(planned
failover)
To forcefully start up
the package even
DR Group does not fail
over and the package does
not start.
DR Group fails over and the
package is started.
The following log message
appears in the package log:
Synchronous
or Enhanced
Asynchronous
Remote failover
when CA link
down or when
the primary site
fails
though data currency
cannot be determined,
create a
The following log message
appears in the package
log:
The role of the device group
on this site is "destination". The
“FORCEFLAG” file in
package directory and
restart the package.
Warning - Unable to get
remote DR group state
state of the replication link is
down and the state of data
because the CA link ismay not be current. Because
down. The role of thethe package startup policy is
device group on this site isAVAILABILITY_PREFERRED, the
"destination". The state ofprogram will attempt to start
up the package. the replication link is down
and the state of data may
not be current. Because the
package startup policy is
DATA_CURRENCY_PREFERRED,
the package is NOT
allowed to start up.
Restart the package
when the merge is
completed.
If the Merge operation completes before WAIT_TIME
expires, DR group is failed over and the package is started.
Otherwise, the DR Group does not failover and the package
SynchronousRemote failover
during merging
is not started. There is no change in this behaviour even if
the FORCEFLAG file is present.
The following log message appears in the package log:
The DR Group is in merging state.
....
The WAIT_TIME has expired.
Error - Failed to failover and swap the role of the device
group.
The package is NOT allowed to start up.
To forcefully start up
the package, create a
If the merge operation
completes before
Waits till WAIT_TIME for the
Merge operation to complete.
Enhanced
Asynchronous
“FORCEFLAG” file inWAIT_TIME expires, thenThe package is started even if
package directory andDR Group fails over andmerge is not completed within
this time. restart the package.the package is started.
Package does not waitOtherwise,, the package is
not started up. for the merge to
Metrocluster package failover/failback scenarios 53